iTunes Gifts 150 pound worth say is invalid

Where did you get them?

d--kh--d123456789 wrote:

3, £50 vouchers are invalid

D-K-H,

See this document:

If you can't redeem your iTunes or Apple Music Gift Card or content code - Apple Support

That document will give you several steps to try. And if none of them work, it has the link for iTunes Customer Service.